Why slow steaming alone isn't enough: the limits of operational optimisation

Slow steaming, weather routing and fuel curve analysis have become standard practice across the global fleet, and as a result, the most easily attainable efficiency gains are largely captured. This insight explains why advisory-only tools are now hitting diminishing returns, and why the next stage of efficiency depends less on better calculations and more on consistent execution.

Operational optimisation maturity levels vary across fleets, but for more digitally advanced vessels and fleets, the most obvious and easily attainable gains have largely been captured.

For example, slow steaming is well understood, weather routing is standard practice, and performance teams have built analysis of fuel curves and voyage deviations into daily routines, while advisory systems provide speed recommendations based on changing conditions.

The International Energy Agency has identified operational measures, such as speed and route optimisation, as among the quickest and most cost-effective tools for reducing maritime energy consumption. As these measures become standard practice, most of the easily achievable efficiency gains have already been captured, leaving only smaller improvements available.

Over the past three years, many forward-thinking operators have explored a range of approaches to voyage optimisation, understanding both the potential and the challenges that come with it. The narrative has gradually shifted from one about concepts - for example, how dynamic voyage planning can save fuel - to one about execution, and the focus is now on how reliably these optimisation plans can be carried out on board.

This is especially clear when it comes to sailing speeds, as much of the industry still relies on a simple ‘slow down and save fuel’ approach. While this approach is often effective and easy to apply, it is taking a sledgehammer to a task that requires a scalpel; it achieves the goal of reduction but ignores the delicate surgical speed adjustments needed for true efficiency.

Under these operating conditions, a large share of the potential gains from speed optimisation can remain unattainable. This makes speed optimisation one of the most visible, but still under-realised, efficiency tools available to operators.

Christos Papadopoulos, Energy and Environmental Engineer at a large global shipping company, explained, “it is not always the lowest sustainable speed that we need to attain. It is how you use speed compared to the commercial and weather conditions and requirements. It is not just lowering speed and slow steaming. It is more than that.”

However, even with increasingly sophisticated and slick models, determining true vessel performance remains a challenge. As Penny Haire, CEO of Tidetech, explained, “you can come up with a fuel consumption curve, but it is a very noisy curve because of all the other variables.”

For example, changing the suggested target speed, power setting, or RPM requires diligence, with suggestions changing every two hours or more. Ongoing adjustment is needed even to maintain a target speed, as weather conditions change and currents shift in strength and direction. Even minor variations can push a vessel away from its optimal position.

As optimisation models improve, further gains depend less on better calculations and more on how consistently recommendations are applied on board. Advisory-only tools can still deliver efficiency recommendations and often are an important first step for operators. However, at this stage, many fleets begin to experience diminishing returns from advisory-only tools, as additional gains become increasingly dependent on consistent execution rather than improved planning alone.

Download the full report ‘Precision In Motion’ and discover why the next stage of fleet efficiency not only depends on better calculations but also, and more importantly, on consistent execution on board.